Ghost file issue

Hi all,When we submit contents to alfresco (3.x community),sometimes it does not move away from the sand box.It does not get submitted either.We call this problem "Ghost file" problem.Does anybody else suffers the same?Is it related to browser we use? (mostly IE 7).Please point me to a right direction.More over it takes a long time to create a new user account for content uploaders.We fail to invite them to webproject thus failing the entire account creation.Does any body have any solution?

Any help is appreciated.Alfresco is doing great by the way!Thanks in advance.Keep up the good work folks!Cheers!